Metronomes are typically used to produce a regulated pulse, usually used to keep a steady beat in musical performances. Musicians typically use metronomes when they practice, in order to keep a standard tempo; i.e., to keep a steady beat throughout the music.
Most modern metronomes are electronic. A typical electronic metronome has a dial or button to control the tempo. Some metronomes can produce two or more distinct sounds. A regular “tick” sound indicates the beat within each measure, and another, distinct sound (e.g., having a higher pitch and/or greater volume) indicates the beginning of each measure. A tempo control adjusts the amount of time separating each beat (typically measured in beats per minute), while another control adjusts the number of beats in each measure.
In an orchestra, or other type of musical ensemble, tempo is typically controlled by a conductor. Conducting is the act of directing a musical performance by way of visible gestures. Use of conventional metronomes in a musical ensemble is not practical since each musician must follow the beat and tempo of the conductor. If multiple musicians each used their own metronome, the metronomes would not be synchronized with each other or with the conductor. Even if the metronomes were synchronized or were set for the same tempo, they would become unsynchronized when the conductor made a change in tempo.
There are disadvantages to relying solely on directions from a conductor. For example, since visible gestures are used, a musician must use eye contact with the conductor, while also reading sheet music. This is even a greater problem where musicians can not maintain eye contact at all times, such as with a marching band.
There is a major disadvantage to sharing a single metronome: in a large auditorium or on a football field, the finite speed of sound causes each musician to hear the single metronome at a tangibly different time.